The present invention relates generally to a rear converter lens of the type that is attached on the image side of a master lens system to increase its focal length, and more particularly to a compact rear converter lens that has a large zoom ratio of about 1.7 to about 2.0 and is well suitable for use on a lens shutter camera.
So far, a typical rear converter lens that is designed to be attached on the image side of a master lens system to increase its focal length has been known from, for instance, JP-A-58-195817, 3-58489, 60-88916, 61-17114, 62-160415 or 63-305316.
Each of the rear converter lenses set forth in these specifications comprises three lenses or, in order from the object side, a first negative lens, a second positive lens and a third negative lens, as is the case with the rear converter lens of the invention. However, the rear converter lenses that are disclosed in JP-A-58-195817, 63-305316, 61-17114 and 60-88916 have a relatively small zoom ratio ranging from about 1.25 to about 1.63. The rear converter lens set forth in JP-A-62-160415 has a high zoom ratio, but involves difficulty in making up for various off-axial aberrations in ordinary photographic modes, because of being designed for use on the master lens system of a camera having a trimming mode. In the rear converter lens described in JP-A-3-58489, the third- and fifth-order coefficients of various aberrations (especially, spherical aberration and coma) that the fourth and fifth surfaces produce are so large that it can be greatly affected by production errors.